Shams inhibits Notch activation in response to increased levels of Delta but not Serrate.

<p>All wings are from females raised at 30°C. (A) Adult wing of a wild-type fly. Wing veins are numbered. The arrow marks the posterior cross-vein (PCV). (B,C) Adding two additional genomic copies of <i>Delta</i> (<i>Dl</i>^<i>gt-wt</i>) (B) or <i>Serrate</i> (<i>Ser</i>^<i>gt-wt</i>) (C) does not affect adult wings. (D) <i>shams</i>^{<i>Δ34/Df</i>} mutants partially lose L4 and L5 wing veins. (E) <i>Dl</i>^{<i>gt-wt/+</i>} <i>shams</i>^{<i>Δ34/Df</i>} animals have a partial loss of L2 vein (red arrow), which is not observed in <i>shams</i>^{<i>Δ34/Df</i>} animals. (F) <i>Ser</i>^{<i>gt-wt/+</i>} <i>shams</i>^{<i>Δ34/Df</i>} wings are indistinguishable from <i>shams</i>^{<i>Δ34/Df</i>} wings (compare to D). (G) Providing an additional genomic copy of <i>Notch</i> (<i>N</i>^<i>gt-wt</i>) induces extra wing vein material at the L2 (red asterisk) and occasionally at the L5 wing vein indicative of Confluens phenotype. (H) <i>N</i>^{<i>gt-wt/+</i>}; <i>Dl</i>^{<i>gt-wt/+</i>} animals exhibit no wing vein defects (compare to G). (I) <i>N</i>^{<i>gt-wt/+</i>}; <i>Ser</i>^{<i>gt-wt/+</i>}animals do not show extra vein around L2 but occasionally show extra wing vein near L5. (J) Providing an additional genomic copy of <i>Notch</i> lacking the functional xylosylation sites (<i>N</i>^{<i>gt-16_20</i>}) induces extra wing vein material near the L5 wing vein. (K) <i>N</i>^{<i>gt-16_20/+</i>}; <i>Dl</i>^{<i>gt-wt/+</i>}animals exhibit a partial loss of L5 (71% penetrant, n = 17). (L) <i>N</i>^{<i>gt-16_20/+</i>}; <i>Ser</i>^{<i>gt-wt/+</i>} wings are indistinguishable from <i>N</i>^{<i>gt-16_20</i>} wings (n = 15) (compare to J).